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Lu, Huayi e6fa411af0 DWS DEV 830.201 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2024-05-16 07:24:04 +00:00

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<a name="EN-US_TOPIC_0000001188482218"></a><a name="EN-US_TOPIC_0000001188482218"></a>
<h1 class="topictitle1">Variable Definition Statement</h1>
<div id="body8662426"><p id="EN-US_TOPIC_0000001188482218__a6f427c9b6b7641f1b078da7186403f00">This section describes the declaration of variables in the PL/SQL and the scope of this variable in codes.</p>
<div class="section" id="EN-US_TOPIC_0000001188482218__s7f9123efed264100b0ec2df42a27a7f4"><h4 class="sectiontitle">Variable Declaration</h4><p id="EN-US_TOPIC_0000001188482218__a32de3764a1c04f93945827d900a79268">For details about the variable declaration syntax, see <a href="#EN-US_TOPIC_0000001188482218__f3705e8285f024bfe8ab480866c9fb57a">Figure 1</a>.</p>
<div class="fignone" id="EN-US_TOPIC_0000001188482218__f3705e8285f024bfe8ab480866c9fb57a"><a name="EN-US_TOPIC_0000001188482218__f3705e8285f024bfe8ab480866c9fb57a"></a><a name="f3705e8285f024bfe8ab480866c9fb57a"></a><span class="figcap"><b>Figure 1 </b>declare_variable::=</span><br><span><img id="EN-US_TOPIC_0000001188482218__i553b3276e2954d24a3ce6beca3629ae0" src="figure/en-us_image_0000001188642254.png"></span></div>
<p id="EN-US_TOPIC_0000001188482218__ae84948cfc96c4abd97e9a16c03fc31d3">The above syntax diagram is explained as follows:</p>
<ul id="EN-US_TOPIC_0000001188482218__ufacaf3fe4514411e90508e200cf51505"><li id="EN-US_TOPIC_0000001188482218__l6947add8536d45aa8dbae54d8a65bc0a"><strong id="EN-US_TOPIC_0000001188482218__en-us_topic_0027042946_b19965232154744_1">variable_name</strong> indicates the name of a variable.</li><li id="EN-US_TOPIC_0000001188482218__l2898e39e7e05422a9638d1b476243a70"><strong id="EN-US_TOPIC_0000001188482218__en-us_topic_0027042946_b19965232154744_5">type</strong> indicates the type of a variable.</li><li id="EN-US_TOPIC_0000001188482218__lce7016558f084a968a2ba9c678533d8f"><strong id="EN-US_TOPIC_0000001188482218__en-us_topic_0027042946_b6086428151213">value</strong> indicates the initial value of the variable. (If the initial value is not given, NULL is taken as the initial value.) <strong id="EN-US_TOPIC_0000001188482218__b761220418491">value</strong> can also be an expression.</li></ul>
<p id="EN-US_TOPIC_0000001188482218__a47ed789d45a8439eba3954b8006ff565">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188482218__s3972a9231e3c4418966c6503213d11c7"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
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<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DECLARE</span>
<span class="w"> </span><span class="n">emp_id</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="w"> </span><span class="mi">7788</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Define a variable and assign a value to it.</span>
<span class="k">BEGIN</span>
<span class="w"> </span><span class="n">emp_id</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="w"> </span><span class="mi">5</span><span class="o">*</span><span class="mi">7784</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Assign a value to the variable.</span>
<span class="k">END</span><span class="p">;</span>
<span class="o">/</span>
</pre></div></td></tr></table></div>
</div>
</div>
<p id="EN-US_TOPIC_0000001188482218__p56696256452">In addition to the declaration of basic variable types, <strong id="EN-US_TOPIC_0000001188482218__b1227372513553">%TYPE</strong> and <strong id="EN-US_TOPIC_0000001188482218__b18342431175515">%ROWTYPE</strong> can be used to declare variables related to table columns or table structures.</p>
<div class="section" id="EN-US_TOPIC_0000001188482218__section940916615495"><h4 class="sectiontitle">%TYPE Attribute</h4><p id="EN-US_TOPIC_0000001188482218__p166641228154919">%TYPE declares a variable to be of the same data type as a previously declared variable (for example, a column in a table). For example, if you want to define a <strong id="EN-US_TOPIC_0000001188482218__b13493124041211">my_name</strong> variable that has the same data type as the <strong id="EN-US_TOPIC_0000001188482218__b185321011141318">firstname</strong> column in the <strong id="EN-US_TOPIC_0000001188482218__b183461227130">employee</strong> table, you can define the variable as follows:</p>
<pre class="screen" id="EN-US_TOPIC_0000001188482218__screen3617174611418">my_name employee.firstname%TYPE</pre>
<p id="EN-US_TOPIC_0000001188482218__p931205175618">In this way, you can declare <strong id="EN-US_TOPIC_0000001188482218__b1715755720181">my_name</strong> even if you do not know the data type of <strong id="EN-US_TOPIC_0000001188482218__b11570465163">firstname</strong> in <strong id="EN-US_TOPIC_0000001188482218__b156961254121620">employee</strong>, and the data type of <strong id="EN-US_TOPIC_0000001188482218__b537613412187">my_name</strong> can be automatically updated when the data type of <strong id="EN-US_TOPIC_0000001188482218__b1743122812180">firstname</strong> changes.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482218__section29981133125818"><h4 class="sectiontitle">%ROWTYPE Attribute</h4><p id="EN-US_TOPIC_0000001188482218__p1777215718594">%ROWTYPE declares data types of a set of data. It stores a row of table data or results fetched from a cursor. For example, if you want to define a set of data with the same column names and column data types as the <strong id="EN-US_TOPIC_0000001188482218__b17565152113283">employee</strong> table, you can define the data as follows:</p>
<pre class="screen" id="EN-US_TOPIC_0000001188482218__screen15104128204217">my_employee employee%ROWTYPE</pre>
</div>
<div class="notice" id="EN-US_TOPIC_0000001188482218__n24f4c41ebd164e7a983b708e1e5fb2e0"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001188482218__a677c52d3b44c4c49a5f41edd9993caa9">If multiple CNs are used, the %ROWTYPE and %TYPE attributes of temporary tables cannot be declared in a stored procedure, because a temporary table is valid only in the current session and is invisible to other CNs in the compilation phase. In this case, a message is displayed indicating that the temporary table does not exist.</p>
</div></div>
<div class="section" id="EN-US_TOPIC_0000001188482218__s89e5f9791fb3457aba42dd7d58bff960"><h4 class="sectiontitle">Scope of a Variable</h4><p id="EN-US_TOPIC_0000001188482218__a5b2baf69095e4ec585dec0d036df830a">The scope of a variable indicates the accessibility and availability of a variable in code block. In other words, a variable takes effect only within its scope.</p>
<ul id="EN-US_TOPIC_0000001188482218__u87369c94e5fa40d3a5a61cc325e82b69"><li id="EN-US_TOPIC_0000001188482218__lef3a8f1114d44008af46a9831bb53673">To define a function scope, a variable must declare and create a <strong id="EN-US_TOPIC_0000001188482218__en-us_topic_0027042946_b43204334143452">BEGIN-END</strong> block in the declaration section. The necessity of such declaration is also determined by block structure, which requires that a variable has different scopes and lifetime during a process.</li><li id="EN-US_TOPIC_0000001188482218__le6e5ddfa147b4932b6ce4b845a4a69a3">A variable can be defined multiple times in different scopes, and inner definition can cover outer one.</li><li id="EN-US_TOPIC_0000001188482218__lc05cb40ad4d4484f82fd6415518ddc31">A variable defined in an outer block can also be used in a nested block. However, the outer block cannot access variables in the nested block.</li></ul>
<p id="EN-US_TOPIC_0000001188482218__a394ce2b1018c44a1885b6942c5e8de78">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188482218__s9f10997b0e1d402d8e68d9f414cec621"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DECLARE</span>
<span class="w"> </span><span class="n">emp_id</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="mi">7788</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Define a variable and assign a value to it.</span>
<span class="w"> </span><span class="n">outer_var</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="mi">6688</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Define a variable and assign a value to it.</span>
<span class="k">BEGIN</span>
<span class="w"> </span><span class="k">DECLARE</span><span class="w"> </span>
<span class="w"> </span><span class="n">emp_id</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="mi">7799</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Define a variable and assign a value to it.</span>
<span class="w"> </span><span class="n">inner_var</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">:</span><span class="o">=</span><span class="mi">6688</span><span class="p">;</span><span class="w"> </span><span class="c1">-- Define a variable and assign a value to it.</span>
<span class="w"> </span><span class="k">BEGIN</span>
<span class="w"> </span><span class="n">dbms_output</span><span class="p">.</span><span class="n">put_line</span><span class="p">(</span><span class="s1">'inner emp_id ='</span><span class="o">||</span><span class="n">emp_id</span><span class="p">);</span><span class="w"> </span><span class="c1">-- Display the value as 7799.</span>
<span class="w"> </span><span class="n">dbms_output</span><span class="p">.</span><span class="n">put_line</span><span class="p">(</span><span class="s1">'outer_var ='</span><span class="o">||</span><span class="n">outer_var</span><span class="p">);</span><span class="w"> </span><span class="c1">-- Cite variables of an outer block.</span>
<span class="w"> </span><span class="k">END</span><span class="p">;</span>
<span class="w"> </span><span class="n">dbms_output</span><span class="p">.</span><span class="n">put_line</span><span class="p">(</span><span class="s1">'outer emp_id ='</span><span class="o">||</span><span class="n">emp_id</span><span class="p">);</span><span class="w"> </span><span class="c1">-- Display the value as 7788.</span>
<span class="k">END</span><span class="p">;</span>
<span class="o">/</span>
</pre></div></td></tr></table></div>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0523.html">Basic Statements</a></div>
</div>
</div>
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